Tetrasubstituted α-pyrone derivatives from the endophytic fungus, Neurospora udagawae.

• Two tetrasubstituted α -pyrones were identified from the endophytic fungus Neurospora udagawae • Udagawanone B constitutes a rare example of a C-4 O -demethylated α -pyrone. • Their antimicrobial and cytotoxic activities are reported. Two new α -pyrone derivatives, udagawanones A (1) and B (2), along with the known compounds (Z)-4-hydroxy-3-(3-hydroxy-3-methylbut-1-en-1-yl)benzoic acid (3), isosclerone (4), cyclo -(L -Leu- L -Pro) (5), and cyclo -(L -Pro- L -Tyr) (6), were isolated from cultures of the endophyte Neurospora udagawae. Their structures were elucidated by extensive spectroscopic methods and single crystal X-ray diffraction. Both compounds feature oxidized functionalities at the C-2 position not previously observed in other tetrasubstituted α -pyrones from fungi. Compound 1 exhibited moderate antibacterial (vs. Staphylococcus aureus) and antifungal (vs. Rhodoturula glutinis) activities and cytotoxicity against KB3.1 cells. [ABSTRACT FROM AUTHOR]